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The urea electro-oxidation reaction (UOR) is emerging as a new energy conversion technology and a promising method for alleviating water eutrophication problems. However, a rationally designed structure of the electrode materials is urgently required to achieve high UOR performance. Herein, P-doped MOF-derived Co3O4 nanowire arrays grown on nickel foam (P-Co3O4/NF) are successfully synthesized via the growth of Co-MOF and subsequent calcination followed by phosphorization treatment. Owing to the optimized electronic structure, the as-prepared P-Co3O4/NF composite exhibits much higher UOR electrocatalytic performance than the undoped Co3O4/NF sample. Beyond this, the meticulous structure of the one-dimensional nanowire arrays and the three-dimensional skeleton structure of nickel foam contribute to the enhanced electrocatalytic activity and stability toward UOR. As a result, the P-Co3O4/NF composite displays a low overpotential of 1.419 V vs. RHE at 50 mA cm−2, a small Tafel slope of 82 mV dec−1, as well as favorable long-term stability over 65,000 s in 1.0 M KOH with 1.0 M urea. This work opens a new avenue in designing non-precious electrocatalysts for high-performance urea electro-oxidation reactions. [ABSTRACT FROM AUTHOR]

The migration and diffusion of Li+, I− and Ag impedes the realization of long‐term operationally stable perovskite solar cells (PSCs). Herein, we report a multifunctional and universal molecular complexation strategy to simultaneously stabilize hole transport layer (HTL), perovskite layer and Ag electrode by the suppression of Li+, I− and Ag migration via directly incorporating bis(2,4,6‐trichlorophenyl) oxalate (TCPO) into HTL. Meanwhile, TCPO co‐doping results in enhanced hole mobility of HTL, advantageous energy band alignment and mitigated interfacial defects, thereby leading to facilitated hole extraction and minimized nonradiative recombination losses. TCPO‐doped regular device achieves a peak power conversion efficiency (PCE) of 25.68 % (certified 25.59 %). The unencapsulated TCPO doped devices maintain over 90 % of their initial efficiencies after 730 h of continuous operation under one sun illumination, 2800 h of storage at 30 % relative humidity, and 1200 h of exposure to 65 °C, which represents one of the best stabilities reported for regular PSCs. This work provides a new approach to enhance the PCE and long‐term stability of PSCs by host–guest complexation strategy via rational design of multifunctional ligand molecules. [ABSTRACT FROM AUTHOR]

Molecular doping of organic semiconductor is a great strategy for significantly regulating the electronic band structure of organic semiconductor while increasing charge mobility and carrier concentration. Here, a facile strategy is presented by introducing 2D g‐C3N5 as a p‐dopant into PM6, improving the charge mobility and hole carrier concentration of PM6. Moreover, the electron transfer between PM6 and g‐C3N5 can effectively downshift the Fermi energy level and highest occupied molecular orbital (HOMO) energy level of PM6, which leads to the increase the built‐in electric field of organic solar cells (OSCs). The addition of g‐C3N5 also effectively enhances the crystallization of active layer, thereby improving the stability of OSCs. As a result, a champion bulk‐heterojunction (BHJ) and layer‐by‐layer (LbL) structure OSCs are successfully achieved featuring a high‐power conversion efficiency of 18.10%/18.25%, simultaneously having excellent device stability. This work shows that introducing a low concentration dopant into organic donor is an effective method for improving the electrical performance of organic donor and the efficiency of OSCs. [ABSTRACT FROM AUTHOR]

The regulation of the local microenvironment in the single‐atom catalysts affords a scheme for accelerating the overall reaction kinetics of electrochemical CO2 reduction reaction (CO2RR), which is of vital importance but remains challenging. Herein, a carbon nanotube‐supported single‐Sn‐atom catalyst (P‐SnN4‐CNT) is developed by a modified pyrolysis procedure with P‐doping into the second coordination shell of SnN4 moiety to modulate the electron structure of metal Sn center. The resulting P‐SnN4‐CNT delivered a high CO partial current density of −380 mA cm−2 with Faradaic efficiency (FE) of CO above 90% across a wide range of −0.5 to −0.8 V versus reversible hydrogen electrode (vs RHE), along with optimal FE (CO) of ≈98.5% at −0.6 V versus RHE in a flow cell. Moreover, P‐SnN4‐CNT achieved an extremely high turnover frequency of 126 471 h−1 with an applied potential of −0.8 V versus RHE, which ranks the best among the reported M─N─C catalysts for electrocatalytic CO2 reduction. The combination of in situ characterization techniques and density functional theory calculation revealed that the doping of P atoms benefited the activation and hydrogenation steps of CO2 and promoted the Sn4+ reduction to Sn2+ during the reaction process, where Sn2+ is identified as the active site for the CO generation. The work provides a clear mechanistic insight for both electron structure optimization and identification of active sites by local microenvironment regulation of single‐Sn‐atom, which shall pave a way for the exploitation of other M─N─C catalysts with high CO2RR performance. [ABSTRACT FROM AUTHOR]

The development of efficient and low-cost alternatives to precious metals as electrocatalysts for electrochemical oxygen evolution (OER), hydrogen evolution (HER) and oxygen reduction (ORR) reactions is an urgent task to solve the current resource shortage problem. Here, we designed a novel enoki shaped catalyst in which FeNi alloy was grown and P was doped on the top of carbon nanotubes (EM-FeNiP@HCNT). The positive repulsion effect between PDDA and Fe2+Ni2+ made FeNi alloy oriented to grow on the top of the carbon nanotubes. C 18 -L-Glu and pyrrole were used as template and carbon source, respectively. After high temperature calcination, C 18 -L-Glu surfactant template was removed, the hollow nanotube structure was formed, the N element was doped and the FeNi ion was reduced to FeNi alloy by one step. EM-FeNiP@HCNT provides superior HER/OER/ORR performance owing to its specific morphology, porous structure, doped P and the synergistic effect between FeNi alloy and P. The prepared EM-FeNiP@HCNT is capable of driving 10 mA cm−2 at 294 (OER) and −224 mV (HER), respectively. The initial and half-wave potential in the ORR reaction require only 0.90 V and 0.78 V. Moreover, the number of transferred electrons of EM-FeNiP@HCNT in the ORR reaction reaches 3.89. The synergistic effect between FeNi and P atom doped carbon substrates provides high electrocatalytic activity and high stability for HER, OER and ORR, which is comparable to or better than that of commercial RuO 2 or Pt/C catalysts. Meanwhile, density functional theory (DFT) calculation shows the composite has low adsorption energy (0.80 V, HER; −2.21 eV, OER/ORR). Therefore, the prepared EM-FeNiP@HCNT shows great application potential as a three-function electrocatalyst. A three-function P-doped catalyst with FeNi alloy directionally grown on the top of carbon nanotubes was prepared; it showed high activity for OER, HER and ORR catalysis. [Display omitted] • Novel catalyst with flammulina mushroom-like structure. • FeNi alloy grows directionally on the top of carbon nanotubes. • Synergistic effect between FeNi alloy and P enhances the catalytic activity. • Catalyst has high specific surface area, large pore structure and high catalytic activity. • High catalytic performance for HER, OER and ORR. [ABSTRACT FROM AUTHOR]

The introduction of molecular doping process is necessary to enhance the optic and electronic properties of organic semiconductors for facilitating charge transport. In particular, since the doping process has a positive influence on the charge transfer interaction between host semiconductor and dopant, improved mobility has been efficiently achieved. Despite its advantages, doping technologies in organic solar cells (OSCs) are emphasized to the development of n‐type dopants used for balancing the electron and hole. In addition, since the bulk‐heterojunction microstructure in OSCs has randomly blended phases of the donor and acceptor, it is important to optimize charge extraction without loss by controlling the morphology. Herein, OSCs by p‐type doping with formic acid (FA) into a photoactive layer is reported. The champion device yields a significantly improved power conversion efficiency from 14.3% to 15.3% with a high fill factor of 71.7%. It is found that the p‐doped photoactive layer exhibits enhanced conductivity, improved carrier mobilities, suppressed charge recombination, and lowered leakage current. The FA simultaneously acts as a film morphology controller of the photoactive layer with enhanced phase separation to transport the charge efficiently. Thus, the doping process with FA can maintain the device performance in stability tests (95.6% remaining). [ABSTRACT FROM AUTHOR]

Selective doping of a single conjugated polymer (CP) to obtain p‐type and n‐type conductive materials would be highly attractive for organic thermoelectric applications, because it will greatly reduce the time and costs of synthesizing different types of CPs. However, this strategy has rarely been investigated. In this study, two CPs are synthesized, designated PTQDPP‐T and PTQDPP‐2FT, based on a newly developed quinoidal unit with thienoisatin as the termini and a thiophene‐flanked diketopyrrolopyrrole (ThDPP) unit as the quinoidal core. The electron‐rich thiophene rings in thienoisatin and the electron delocalization induced by thienoisatin resulted in polymers with high‐lying highest occupied molecular orbital, and the electron‐deficient nature of ThDPP unit and its quinoidal backbone endowed the polymers with low‐lying lowest unoccupied molecular orbitals. As a result, both polymers can be p‐type and n‐type doped. Because of its high mobility, doped PTQDPP‐2FT performed better in organic thermoelectric devices than the doped PTQDPP‐T. After being doped with FeCl3 and N‐DMBI, PTQDPP‐2FT showed p‐type and n‐type power factors of 278.2 and 2.37 µW m−1 K−2, respectively. These are the best for bipolar (p‐type and n‐type) performances that obtained by selective doping of a single polymer. [ABSTRACT FROM AUTHOR]

Out-of-plane p-n heterojunctions based on two-dimensional layered materials (2DLMs) with unusual physical characteristics are attracting extensive research attention for their application as photodetectors. However, the present fabrication method based on 2DLMs produces out-of-plane p-n homojunction devices with low photoresponsivity and detectivity. This work reports an ultrasensitive phototransistor based on a laser-induced p-doped WSe2/MoS2 van der Waals heterojunction. The laser treatment is used for p-doping WSe2 nanoflakes using high work function WOx. Then, an n-type MoS2 nanoflake is transferred onto the resulting p-doped WSe2 nanoflake. The built-in electric field of p-doped WSe2/MoS2 is stronger than that of pristine WSe2/MoS2. The p-n junction between p-doped WSe2 and MoS2 can separate more photogenerated electron–hole pairs and inject more electrons into MoS2 under laser illumination than pristine WSe2/MoS2. Thus, a high photoresponsivity (R) of ~1.28 × 105 A·W−1 and high specific detectivity (D*) of ~7.17 × 1013 Jones are achieved under the illumination of a 633 nm laser, which is approximately two orders higher than the best phototransistor based on a WSe2/MoS2 heterojunction. Our work provides an effective and simple method to enhance photoresponsivity and detectivity in two-dimensional (2D) heterojunction phototransistors, indicating the potential applications in fabricating high-performance photodetectors based on 2DLMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of catalysts with different P doping amounts were prepared. • P doping significantly promoted the activation efficiency of PMS. • Co-O-P weakened the strength of Co-O bond to promote the conversion of Co2+. • Local electron enrichment enhanced the electron transfer ability of P x -Co 3 O 4 to PMS. In this study, a series of P x -Co 3 O 4 catalysts were prepared by regulating the doping level of P in Co 3 O 4. The results showed that the addition of P significantly affected the activation efficiency of permonosulfate (PMS). 100 % of p-nitrobenzaldehyde (4-NBA) was degraded within 40 min at 0.4 g/L PMS and 0.05 g/L P 3 -Co 3 O 4. The influence mechanism of P doping on oxidation process of P x -Co 3 O 4 /PMS system was revealed through physicochemical characterization, experimental analysis, and theoretical calculation. Specifically, P doping first increased the contact frequency between P x -Co 3 O 4 and PMS by inducing O V production. In addition, P doping promoted the formation of Co-O-P bond on the catalyst. Co-O-P could weaken the strength of Co-O bond and promoted the conversion of available Co Species—Co2+. Meanwhile, Co-O-P induced local electron enrichment enhanced the electron transfer ability of P x -Co 3 O 4 to PMS, and thus weakened the energy barrier of PMS conversion to free radicals. Our research provides a new strategy and theoretical guidance for the preparation of novel and efficient heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Single-atomic Fe-N4 is the well-acknowledged active site in iron-nitrogen-carbon (Fe-N-C) material for oxygen reduction reaction (ORR). The adjusting of the electronic distribution of Fe-N4 is promising for further enhancing the performance of the Fe-N-C catalyst. Herein, a phosphorus (P)-doped Fe-N-C catalyst with penta-coordinated single atom sites (FeNPC) is reported for efficient oxygen reduction. Fe K-edge X-ray absorption spectroscopy (XAS) verifies the coordination environment of single Fe atom, while density functional theory (DFT) calculations reveal that the penta-coordination and neighboring doped P atoms can simultaneously change the electronic distribution of Fe-N4 and its adsorption strength of key intermediates, reducing the reaction-free energy of the potential-limiting step. Electrochemical tests validate the remarkable intrinsic ORR activity of FeNPC in alkaline media (a half-wave potential (E1/2) of 0.904 V vs. reversible hydrogen electrode (RHE) and limited current density (JL) of 6.23 mA·cm−2) and an enhanced ORR performance in neutral (E1/2 = 0.751 V, JL = 5.27 mA·cm−2) and acidic media (E1/2 = 0.735 V, JL = 5.82 mA·cm−2) with excellent stability, highlighting the benefits of optimizing the local environment of single-atomic Fe-N4. [ABSTRACT FROM AUTHOR]

Three different cathodic materials for the hydrogen evolution reaction (HER) consisting of Ru nanoparticles (NPs) supported onto a bare and two doped reduced graphene oxides (r-GO) have been studied. Ru NPs have been synthesized in situ by means of the organometallic approach in the presence of each reduced graphene support (bare (rGO), N-doped (NH 2 -rGO) and P-doped (P-rGO)). (HR)TEM, EDX, EA, ICP-OES, XPS, Raman and NMR techniques have been used to fully characterize the obtained rGO-supported Ru materials. These materials have been deposited onto a glassy carbon rotating disk electrode (GC-RDE) to assess their HER electrocatalytic activity at acidic pH. The results show that all three materials are stable under reductive conditions for at least 12 h, and that the heteroatom-doping of the graphene structure extremely increases the activity of the electrodes, especially for the case of Ru@P-rGO, where the overpotential at -10 mA·cm -2 decreases to only 2 mV. Realistic (based on experimental compositional data) modeling of the three rGO supports combined with DFT computational analysis of the electronic and electrocatalytic properties of the hybrid nanocatalysts allows attributing the observed electrocatalytic performances to a combination of interrelated factors such as the distance of the Ru atoms to the dopped rGO support and the hydride content at the Ru NP surface.

It is commonly believed that the spontaneous p‐doping in Sn‐based perovskites is caused by Sn vacancies. By performing rigorous first‐principles calculations for a prototypical Sn‐based perovskite CsSnI3, we reveal that, in fact, the defects dominating p‐doping are Cs vacancies. The reason that adding extra Sn2+ could reduce p‐doping is that Cs and Sn present the same changing trend in terms of chemical potentials, and thus inhibiting the formation of Sn vacancies will also limit the formation of Cs vacancies. Moreover, we show that I vacancies are the dominant nonradiative recombination centers, and can result in sizable nonradiative losses, which explains why the experimentally measured carrier lifetime is only a few nanoseconds even if p‐doping is suppressed. This work provides new insights into the origins of p‐doping and nonradiative recombination in CsSnI3, and suggests that minimizing the formation of Cs and I vacancies is critical to realizing the best device performance. [ABSTRACT FROM AUTHOR]

It is commonly believed that the spontaneous p‐doping in Sn‐based perovskites is caused by Sn vacancies. By performing rigorous first‐principles calculations for a prototypical Sn‐based perovskite CsSnI3, we reveal that, in fact, the defects dominating p‐doping are Cs vacancies. The reason that adding extra Sn2+ could reduce p‐doping is that Cs and Sn present the same changing trend in terms of chemical potentials, and thus inhibiting the formation of Sn vacancies will also limit the formation of Cs vacancies. Moreover, we show that I vacancies are the dominant nonradiative recombination centers, and can result in sizable nonradiative losses, which explains why the experimentally measured carrier lifetime is only a few nanoseconds even if p‐doping is suppressed. This work provides new insights into the origins of p‐doping and nonradiative recombination in CsSnI3, and suggests that minimizing the formation of Cs and I vacancies is critical to realizing the best device performance. [ABSTRACT FROM AUTHOR]

It is commonly believed that the spontaneous p‐doping in Sn‐based perovskites is caused by Sn vacancies. By performing rigorous first‐principles calculations for a prototypical Sn‐based perovskite CsSnI3, we reveal that, in fact, the defects dominating p‐doping are Cs vacancies. The reason that adding extra Sn2+ could reduce p‐doping is that Cs and Sn present the same changing trend in terms of chemical potentials, and thus inhibiting the formation of Sn vacancies will also limit the formation of Cs vacancies. Moreover, we show that I vacancies are the dominant nonradiative recombination centers, and can result in sizable nonradiative losses, which explains why the experimentally measured carrier lifetime is only a few nanoseconds even if p‐doping is suppressed. This work provides new insights into the origins of p‐doping and nonradiative recombination in CsSnI3, and suggests that minimizing the formation of Cs and I vacancies is critical to realizing the best device performance. [ABSTRACT FROM AUTHOR]

It is commonly believed that the spontaneous p‐doping in Sn‐based perovskites is caused by Sn vacancies. By performing rigorous first‐principles calculations for a prototypical Sn‐based perovskite CsSnI3, we reveal that, in fact, the defects dominating p‐doping are Cs vacancies. The reason that adding extra Sn2+ could reduce p‐doping is that Cs and Sn present the same changing trend in terms of chemical potentials, and thus inhibiting the formation of Sn vacancies will also limit the formation of Cs vacancies. Moreover, we show that I vacancies are the dominant nonradiative recombination centers, and can result in sizable nonradiative losses, which explains why the experimentally measured carrier lifetime is only a few nanoseconds even if p‐doping is suppressed. This work provides new insights into the origins of p‐doping and nonradiative recombination in CsSnI3, and suggests that minimizing the formation of Cs and I vacancies is critical to realizing the best device performance. [ABSTRACT FROM AUTHOR]

P-CoS 1-x with S vancancy was obtained by one-step hydrothermal sulfurization and further phosphating and reduction treatment. The electrode shows a high electronic conductivity and excellent electrochemical performance and OER performance. [Display omitted] Cobalt sulfide (CoS) is a promising battery-type material for electrochemical energy storage. However, the poor conductivity and slow charge transfer kinetics as well as the deficiency of electrochemically active sites seriously limit their applications. Herein, a class of the P-doping induced hexagonal CoS nanosheets with S defects (P-CoS 1-x) derived from Co-based metal organic frameworks (MOFs) supported on carbon nanotube film (CNT) is designed and prepared. The density functional theory (DFT) simulations show the higher conductivity of the P-CoS 1-x electrode than CoS. Taking advantage of the synergistic effects of the high conductive P-CoS nanosheets with rich S defects and the flexible CNT, the P-CoS 1-x /CNT electrode exhibits a high reversible capacity of 4.3F cm−2, remarkable rate capability, and outstanding long-term cyclability. Impressively, the flexible asymmetric supercapacitor (ASC) based on P-CoS 1-x //CoS@PPy achieves a satisfying energy density of 0.18 mWh cm−2 and high bending stability. The electrocatalytic result suggests that the P-CoS 1-x possesses the lowest overpotential and the smallest Tafel slope. This vacancy engineering strategy also provides a new insight into active materials and should be beneficial for the design of the next generation of energy storage devices. [ABSTRACT FROM AUTHOR]

In an article published in Advanced Energy Materials, researchers Jie Yin, Xuning Li, and their colleagues discuss their findings on the engineering of a single-Sn-atom catalyst for efficient CO2 electroreduction. By doping the catalyst with P atoms, the researchers were able to enhance its performance in reducing CO2. The doping process promoted the reduction of Sn4+ to Sn2+, with the Sn2+ identified as the active site for CO generation. This research provides valuable insights into the development of catalysts for CO2 electroreduction. [Extracted from the article]

Spiro‐OMeTAD is one of the most used hole transport layers (HTLs) in high efficiency n‐i‐p perovskite solar cells (PSCs). However, due to the unsatisfactory conductivity of pristine Spiro‐OMeTAD, additives such as tert‐butylpyridine (tBP) and lithium bis (trifluoromethylsulfonyl)‐imide (LiTFSI) are required to improve its hole transportation. The hygroscopic nature of these additives inevitably deteriorates the device's stability. Here, it is shown that by adding fluorinated graphene (FG) into the Li‐TFSI and tBP doped Spiro‐OMeTAD, both efficiency and stability of the PSCs are significantly enhanced. Using the FG incorporated Spiro‐OMeTAD HTL, the power conversion efficiency (PCE) of the PSC reaches 21.92%, which is 11.8% higher than the original device. The FG not only improves the hole mobility of Spiro‐OMeTAD but also effectively reduces the amount of lithium ions in the perovskite layer and improves the hydrophobicity of the HTL. The FG incorporating cell shows better stability, maintaining 90% of initial efficiency over a 2400 h test in ambient conditions with 25% humidity. Finally, it is further demonstrated that the valence band of FG incorporated Spiro‐OMeTAD HTL has a positive effect on PSCs with a 2D interfacial layer, achieving an impressive PCE of 23.14% and a Voc of 1.226 V. [ABSTRACT FROM AUTHOR]

In this manuscript, we have shown the growth and extensive structural and optical characteristic of the uniformly Mg-doped Al0.23Ga0.77N (UV-A region, λ ∼ 323 nm) nanowire. The Kelvin probe force microscopy was employed to determine the profile of holes in p-type AlGaN nanowires by measuring the work function changes induced by Mg incorporation. The influence of surface band bending on doping concentration has thoroughly been discussed. Our experiment confirms the homogeneous incorporation of Mg throughout the nanowire without any top surface Mg segregation. In this work, we have also demonstrated a comprehensive analysis of acceptor states induced thermal quenching behaviour in the optical transition of Mg-doped AlGaN nanowire. We propose a phenomenological model, based on the rate equation which confirms that achieving higher ‘hole’ (p-doping) concentration in AlGaN nanowire (>1018 cmâˆ'3) is more conducive than the planar counterpart if the growth of NWs is carried out at optimized process conditions. This rate equation-based model has also demonstrated the influence of sidewall surface passivation in those AlGaN nanowires. [ABSTRACT FROM AUTHOR]

This manuscript reports the porous P-Fe 7 S 8 nanospheres synthesized by phosphorus doping into Fe 3 S 4 nanospheres obtained from one-step vulcanization strategy. The structure performs well in supercapacitor, and the Ni x Fe 1-x S samples synthesized by the same vulcanization strategy show excellent electrocatalysis performance in oxygen evolution reaction. [Display omitted] Transition metal sulfides are promising battery-type materials for electrochemical energy storage and a great electrocatalyst for oxygen evolution reaction (OER). However, the poor conductivity and sluggish reaction kinetic as well as the deficiency of electrochemically active sites hinder the practical application of Fe x S y. Herein, we design Fe 7 S 8 porous nanoparticles with surface phosphate ions and enriched sulfur-vacancies (P-Fe 7 S 8), which is reported as a new high-specific-capacity material for asymmetric supercapacitor. Benefiting from the merits of substantially improved electrical conductivity and increased active sites, the optimized P-Fe 7 S 8 negative electrode delivers ultra-high specific capacitance of 804.7F/g at 0.4 mA. Moreover, the assembled NiS//P-Fe 7 S 8 ASC presents an impressive specific capacitance of 335.9F/g at 1.2 A/g, a high energy density of 134.8 Wh/kg at a power density of 1042.1 W/kg, and great flexibility under different bending angles. Furthermore, the one-step vulcanization process is provided with universal applicability for the synthesis of Ni x Fe 1-x S bimetallic sulfide. With the synergy effect produced by the bimetal, the Ni 0.5 Fe 0.5 S hollow porous nanoparticles exhibit the remarkable activity of oxygen evolution reaction with a low overpotential of 174 mV at 10 mA cm−2 and Tafel slope of 41 mV dec−1. This simple method provides new insight into the synthesis of novel multifunctional metal sulfide nanomaterials. [ABSTRACT FROM AUTHOR]

Out-of-plane p-n heterojunctions based on two-dimensional layered materials (2DLMs) with unusual physical characteristics are attracting extensive research attention for their application as photodetectors. However, the present fabrication method based on 2DLMs produces out-of-plane p-n homojunction devices with low photoresponsivity and detectivity. This work reports an ultrasensitive phototransistor based on a laser-induced p-doped WSe2/MoS2 van der Waals heterojunction. The laser treatment is used for p-doping WSe2 nanoflakes using high work function WOx. Then, an n-type MoS2 nanoflake is transferred onto the resulting p-doped WSe2 nanoflake. The built-in electric field of p-doped WSe2/MoS2 is stronger than that of pristine WSe2/MoS2. The p-n junction between p-doped WSe2 and MoS2 can separate more photogenerated electron–hole pairs and inject more electrons into MoS2 under laser illumination than pristine WSe2/MoS2. Thus, a high photoresponsivity (R) of ~1.28 × 105 A·W−1 and high specific detectivity (D*) of ~7.17 × 1013 Jones are achieved under the illumination of a 633 nm laser, which is approximately two orders higher than the best phototransistor based on a WSe2/MoS2 heterojunction. Our work provides an effective and simple method to enhance photoresponsivity and detectivity in two-dimensional (2D) heterojunction phototransistors, indicating the potential applications in fabricating high-performance photodetectors based on 2DLMs.

Initial reversibility and excellent capacity retention are the key requirements for the success of high‐capacity electrode materials in high‐performance Li‐ion batteries and pose a number of challenges to development. Silicon has been regarded as a promising anode material because of its outstanding theoretical capacity. However, it suffers from colossal volume change and continuous formation of unstable solid electrolyte interphases during lithiation/delithiation processes, which eventually result in low initial Coulombic efficiency (ICE) and severe capacity decay. To circumvent these challenges, a new sandwich Si anode (SiOx/Si/SiOx) free from prelithiation is designed and fabricated using a combination of P‐doping and SiOx layers. This new anode exhibits high conductivity and specific capacity compared to other Si thin‐film electrodes. Cells with SiOx/Si/SiOx anodes deliver the highest presently known ICE value among Si thin‐film anodes of 90.4% with a charge capacity of 3534 mA h g−1. In addition, the SiOx layer has sufficient mechanical stability to accommodate the large volume change of the intervening Si layer during charge‐discharge cycling, exhibiting high potential for practical applications of Si thin‐film anodes. [ABSTRACT FROM AUTHOR]

Abstract We investigated the electrical and optoelectronic characteristics of ambipolar WSe2 field-effect transistors (FETs) via facile p-doping process during the thermal annealing in ambient. Through this annealing, the oxygen molecules were successfully doped into the WSe2 surface, which ensured higher p-type conductivity and the shift of the transfer curve to the positive gate voltage direction. Besides, considerably improved photoswitching response characteristics of ambipolar WSe2 FETs were achieved by the annealing in ambient. To explore the origin of the changes in electrical and optoelectronic properties, the analyses via X-ray photoelectron, Raman, and photoluminescence spectroscopies were performed. From these analyses, it turned out that WO3 layers formed by the annealing in ambient introduced p-doping to ambipolar WSe2 FETs, and disorders originated from the WO3/WSe2 interfaces acted as non-radiative recombination sites, leading to significantly improved photoswitching response time characteristics.

In the research field on materials for energy solutions, the exploitation of organic compounds and polymers is of great interest, especially in view of a more eco-sustainable development. In this context, the 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) molecule actively participates in the optimization of many optoelectronic devices based on such elements, thanks to its electrical properties. In this paper, we report a study on its optical properties, in particular demonstrating fluorescence emission from solutions containing F4TCNQ. This phenomenon is equally relevant, together with the effects on electrical conductivity, in the design of systems for energy technology. The results we present here offer new insights in the phenomenological picture of this molecule and can sharpen its applicability.

Phosphorus-doped activated carbon (P@AC), prepared by wet impregnation method, can serve as efficient metal-free catalyst for the dehydroaromatization of n-hexane to benzene under mild conditions. The effect of phosphorus amount and phosphorus sources including phenylphosphonic acid (PPOA), phosphorus acid (H3PO4), triphenylphosphine (TPP), and tributylphosphine (TBP) on catalytic performance of P@AC were investigated. Combining with characterization analysis, functional groups containing -P(O)(OH) on the carbon surface are believed to be the active sites for dehydroaromatization catalysis.

We have investigated the physicochemical properties of the p-type delafossite conductors, CuAlO2, and the possibility of charge carrier enriching to the delafossite. The oxygen partial pressure was a critical condition to get the stoichiometric CuAlO2 during the synthesis process, Po2 = 0.175 atm at 1313 K. A series of CuAl1−xGaxO2 (0 ≤ x ≤ 0.05) were prepared to study the impurity effect of Ga3+ in the delafossite. The Cu2+ ion created in the delafossite by the homovalent substitution—Al3+ (67.5 pm in diameter) could be replaced by Ga3+ (76.0 pm in diameter) up to x = 0.03 in CuAl1−xGaxO2. The different charge densities (+ ion charge/radius of ion) between the 3 + ions might be the reason for the formation of Cu2+in the Ga-doped CuAlO2. But the distinctive conductivity enhancement by the Ga doping was not observed. The other type of p-doping, inserting excess oxygen into the lattice (CuAlO2+x), was observed near the sample's surface due to the low diffusion rate of the oxygen in the delafossite lattice. [ABSTRACT FROM AUTHOR]

Polymer photodetectors with photomultiplication (PM‐PPDs) are prepared with PC71BM:P3HT (1:100, wt/wt) active layers containing efficient hole‐transport channels and large amount of isolated electron traps. The solid additive F6TCNNQ is incorporated into PC71BM:P3HT blend films with rather low content of 0.02 wt%. The external quantum efficiency (EQE) and response speed of PM‐PPDs with F6TCNNQ additive in the active layer are much larger than those of PM‐PPDs without F6TCNNQ additive under the same bias. The EQE values at 400 and 625 nm can reach 5240% and 3050% for the PM‐PPDs with F6TCNNQ in active layers under −9 V bias, which is among the highest values for PM‐PPDs under the same bias. The performance improvement of PM‐PPDs with F6TCNNQ is primarily ascribed to the enhanced hole mobility in the active layer, leading to the increased response speed with rise time of 27.7 ms and fall time of 85 ms. This work indicates that performance of PM‐PPDs can be markedly enhanced by using p‐doping with strong oxidizing agents, beneficial for an enhancement in hole mobility in F6TCNNQ:PC71BM:P3HT active layers. [ABSTRACT FROM AUTHOR]

The binary transition metal oxides have attracted great attention because of their considerable energy and power densities. However, they suffer from low reaction kinetics and large volume change, limiting their practical energy applications. The construction of a mesoporous structure with a large surface area, the development of a carbon matrix, as well as heteroatom doping can effectively overcome the above challenges. Herein, the synthesis of phosphorous‐containing Fe2VO4/nitrogen‐doped carbon mesoporous nanowires (P‐Fe2VO4/NCMNWs) is reported. In this unique structure, the atomic‐level P‐doping could increase the conductivity of Fe2VO4 by reducing its band gap, which is confirmed by DFT calculations. Furthermore, the phosphorus can covalently "bridge" the carbon layer and Fe2VO4 through P−C and Fe−O−P bondings. As a result, this anode material exhibits a high capacity (1002 mA h g−1 at 0.5 A g−1 after 250 cycles), excellent rate performance (448 mA h g−1 at 10 A g−1), and prominent long‐term cycling stability (533 mA h g−1 at 5 A g−1 after 500 cycles, 364 mA h g−1 at 10 A g−1 after 1000 cycles). All of these attractive features make the P‐Fe2VO4/NCMNWs a promising electrode material for high‐performance lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Derivatives of the hexacyano‐[3]‐radialene anion radical (CN6‐CP•−) emerge as a promising new family of p‐dopants having a doping strength comparable to that of archetypical dopant 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyano‐quinodimethane (F4TCNQ). Here, mixed solution (MxS) and sequential processing (SqP) doping methods are compared by using a model semiconductor poly(3‐hexylthiophene) (P3HT) and the dopant CN6‐CP•−NBu4+ (NBu4+ = tetrabutylammonium). MxS films show a moderate yet thickness‐independent conductivity of ≈0.1 S cm−1. For the SqP case, the highest conductivity value of ≈6 S cm−1 is achieved for the thinnest (1.5–3 nm) films whereas conductivity drops two orders of magnitudes for 100 times thicker films. These results are explained in terms of an interfacial doping mechanism realized in the SqP films, where only layers close to the P3HT/dopant interface are doped efficiently, whereas internal P3HT layers remain essentially undoped. This structure is in agreement with transmission electron microscopy, atomic force microscopy, and Kelvin probe force microscopy results. The temperature‐dependent conductivity measurements reveal a lower activation energy for charge carriers in SqP samples than in MxS films (79 meV vs 110 meV), which could be a reason for their superior conductivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly sensitive near-infrared organic photodetector is demonstrated by the introduction of a p-doped hole transport layer. • The p-doping strategy leads to an upward shift of the energy levels, which increases the reverse electron injection barrier and charge collection efficiency simultaneously, thus augmenting the external quantum efficiency. • With improved conductivity and reduced trap states, the optimized device exhibits an ultra-low dark current density of 0.13nA cm−2 at −1 V and a highest specific detectivity of 6.02 × 1013 Jones at 800 nm. Organic photodetectors (OPDs) have gained increasing interest for their remarkable opto-electronic performances and compatibility with flexible devices. However, the commonly occurring high dark current and low detectivity severely reduce the performance and hinder the commercialization of near-infrared photodetectors. Here, we introduce a universal strategy of a p-doped hole transport layer to realize highly sensitive photodetectors. The dark current is significantly reduced by mitigating the reverse charge injection. As a result, the optimized OPD consisting of PM6:Y6 as active layer and 1 nm F 4 TCNQ p-doped PBTTT as hole transport layer exhibits an ultra-low dark current of 0.13nA cm−2 at −1 V, which is one the best performed near-infrared OPDs ever reported and comparable to commercialized silicon photodetectors. A maximum specific detectivity of 6.02 × 1013 Jones at 800 nm is achieved with improved charge collection efficiency and reduced trap states. The potential commercial application in image sensing is presented by integrating optimized OPDs into high-pixel-density arrays, further demonstrating the significance of the improved detection characteristics in capturing high-quality sample images with this technology. The insights provided in our study have profound implications for the design and optimization of high-performance OPDs spanning the ultraviolet to near-infrared range. [ABSTRACT FROM AUTHOR]

The electronic properties of single-layer, CVD-grown graphene were modulated by deep ultraviolet (DUV) light irradiation in different radiation environments. The graphene field-effect transistors (GFETs), exposed to DUV in air and pure O2, exhibited p-type doping behavior, whereas those exposed in vacuum and pure N2 gas showed n-type doping. The degree of doping increased with DUV exposure time. However, n-type doping by DUV in vacuum reached saturation after 60 min of DUV irradiation. The p-type doping by DUV in air was observed to be quite stable over a long period in a laboratory environment and at higher temperatures, with little change in charge carrier mobility. The p-doping in pure O2 showed ~15% de-doping over 4 months. The n-type doping in pure N2 exhibited a high doping effect but was highly unstable over time in a laboratory environment, with very marked de-doping towards a pristine condition. A lateral pn-junction of graphene was successfully implemented by controlling the radiation environment of the DUV. First, graphene was doped to n-type by DUV in vacuum. Then the n-type graphene was converted to p-type by exposure again to DUV in air. The n-type region of the pn-junction was protected from DUV by a thick double-coated PMMA layer. The photocurrent response as a function of Vg was investigated to study possible applications in optoelectronics.

Abstract In this study, a near‐infrared photodetector featuring a high photoresponsivity and a short photoresponse time is demonstrated, which is fabricated on rhenium diselenide (ReSe2) with a relatively narrow bandgap (0.9–1.0 eV) compared to conventional transition‐metal dichalcogenides (TMDs). The excellent photo and temporal responses, which generally show a trade‐off relation, are achieved simultaneously by applying a p‐doping technique based on hydrochloric acid (HCl) to a selected ReSe2 region. Because the p‐doping of ReSe2 originates from the charge transfer from un‐ionized Cl molecules in the HCl to the ReSe2 surface, by adjusting the concentration of the HCl solution from 0.1 to 10 m, the doping concentration of the ReSe2 is controlled between 3.64 × 1010 and 3.61 × 1011 cm−2. Especially, the application of the selective HCl doping technique to the ReSe2 photodetector increases the photoresponsivity from 79.99 to 1.93 × 103 A W−1, and it also enhances the rise and decay times from 10.5 to 1.4 ms and from 291 to 3.1 ms, respectively, compared with the undoped ReSe2 device. The proposed selective p‐doping technique and its fundamental analysis will provide a scientific foundation for implementing high‐performance TMD‐based electronic and optoelectronic devices.

Iron-based materials are effective for the reductive removal of the disinfection byproduct bromate in water, while the construction of highly stable and active Fe-based materials with wide pH adaptability remains greatly challenging. In this study, highly dispersed iron phosphide-decorated porous carbon (Fe 2 P( x )@P( z )NC- y ) was prepared via the thermal hydrolysis of Fe@ZIF-8, followed by phosphorus doping (P-doping) and pyrolysis. The reduction performances of Fe 2 P( x )@P( z )NC- y for bromate reduction were evaluated. Characterization results showed that the Fe, P, and N elements were homogeneously distributed in the carbonaceous matrix. P-doping regulated the coordination environment of Fe atoms and enhanced the conductivity, porosity, and wettability of the carbonaceous matrix. As a result, Fe 2 P( x )@P(1.0)NC-950 exhibited enhanced reactivity and stability with an intrinsic reduction kinetic constant ( k int )@NC-950 without P-doping. Furthermore, Fe x )@NC-950 without P-doping. Furthermore, Fe 2 P(0.125)@P(1.0)NC-950 displayed superior reduction efficiency and prominent stability with very low Fe leaching (4.53-22.98 μg L -1 ) in a wide pH range of 4.0-10.0. The used Fe 2 P(0.125)@P(1.0)NC-950 could be regenerated by phosphating, and the regenerated Fe 2 P(0.125)@P(1.0)NC-950 maintained 85% of its primary reduction activity after five reuse cycles. The study clearly demonstrates that Fe 2 P-decorated porous carbon can be applied as a robust and stable Fe-based material in aqueous bromate reduction.

The development of electrically pumped semiconductor diode lasers emitting at the ultraviolet (UV)-B and -C spectral bands has been an active area of research over the past several years, motivated by a wide range of emerging applications. III-Nitride materials and their alloys, in particular AlGaN, are the material of choice for the development of this ultrashort-wavelength laser technology. Despite significant progress in AlGaN-based light-emitting diodes (LEDs), the technological advancement and innovation in diode lasers at these spectral bands is lagging due to several technical challenges. Here, the authors review the progress of AlGaN electrically-pumped lasers with respect to very recent achievements made by the scientific community. The devices based on both thin films and nanowires demonstrated to date will be discussed in this review. The state-of-the-art growth technologies, such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD); and various foreign substrates/templates used for the laser demonstrations will be highlighted. We will also outline technical challenges associated with the laser development, which must be overcome in order to achieve a critical technological breakthrough and fully realize the potential of these lasers.

The $p$ -type doping in base regions of transistor lasers (TLs) plays an essential role in both the electrical and optical functionalities. The holes in heavily $p$ -doped bases lay the ground for not only the control of current signals but also stimulated emission of lasing modes. In this paper, however, we show that an exceedingly high doping level does not further enhance the radiative recombination in TLs. With heavy doping, the distorted band profile induced by the slight charge separation of holes and ionized acceptors results in no bound valence subbands in the quantum well (QW). This effect stops holes from entering the QW, and most radiative transitions take place inefficiently between bound electrons in the QW and quasi-free holes in the base. As a result, the radiative lifetime is only shortened to the (sub-) nanosecond range, suggesting that the previously reported picosecond carrier lifetime of TLs might originate from other recombination processes. [ABSTRACT FROM AUTHOR]

• Differential capacitance in ITO/P3HT/Al diodes recorded by C−V measurements. • Electron traps and p-doping in P3HT thin-films caused by oxygen molecules. • Change in the P3HT´s Fermi level and of its alignment with the electrodes work functions due to the action of oxygen. The origin of capacitance peaks in C–V measurements often observed in organic thin-film diodes is still waiting for a definitive explanation. It has been reported that one of two-peak C–V detected in p-doped material based devices are caused by involuntary doping, while the second one is attributed to trapped carriers. In this study, we show a ITO/P3HT/Al diode exhibiting one C–V peak at approximately 0.48 V, in both non-exposed and air-exposed devices. The second peak, (around 1.5 V) arises when the device is exposed to air, and increases significantly with exposure time. We suggest that the second peak is originated by a volumetric p-doping of P3HT due to the action of oxygen and the formation of electrons deep traps. A simple model to explain the C–V experiments is presented and is in agreement with this hypothesis. [ABSTRACT FROM AUTHOR]

• Heteroatom substitution is a strategy to tune properties of polythiophene analogues. • Doping of poly(3-alkylchalogenphene) thin films improves their conductivities. • Less dopant is required to vastly improve conductivity of poly(3-alkyltellurophene). • Dopant anion size affects the doping efficiency. Heavy heteroatom substitution is a strategy for tailoring crystalline packing, carrier mobilities, and optoelectronic properties of the poly(3-chalcogenophenes) (P3AEs). In this study, the structure-property relationship is explored between S, Se, and Te substituted P3AEs and how heteroatom substitution affects the integration of dopants. Two oxidants with were used to positively-dope the P3AEs: iron(III) chloride and iron(III) p -toluenesulfonate hexahydrate. We observe that the size of dopant anion affects the doping efficiency, topology, and morphology of the P3AEs depending on the heteroatom substituted. Outstandingly, poly(3-alkyltellurophene) dopes most efficiently greatly improving its conductivity at low doping concentrations. Moreover, polymers doped with iron(III) p -toluenesulfonate hexahydrate all had considerable improvements at lower doping concentrations. Lightly doped P3AEs could be favorably incorporated into transistors, photovoltaics, and thermoelectrics without compromising conductivity or causing unwanted side-reactions between excess dopant and other components of the device. [ABSTRACT FROM AUTHOR]

• The n-type donor (P) is used to modulate the structure and properties of carbon dots(P-CDs). • P-doping helps to increase the crystallinity of carbon dots and facilitates electron transport. • The photocatalytic mimetic enzyme activity of P-CDs is mediated by superoxide radicals (O 2 •−). • P-CDs possess effective antibacterial activity against E. coli and S. aureus. Bacterial contamination poses a serious and global threats to public health. Due to broad-band antimicrobial capacity and unspecific tissue interaction, antibacterial nanomaterials offer promising alternative and green strategies to resist bacterial contamination. Herein, an enhanced metal-free carbon-dots nanozymes, i.e., m-aminophenol based phosphoric acid doping carbon dots (P-CDs), with excellent photoresponse enzyme-like properties are designed through a simple one-pot hydrothermal method for highly effective antimicrobial. Developed P-CDs exhibited superior photoresponse oxidase-like activity, which may attribute to the higher crystallinity conferred by P-doping. Interestingly, the generation of superoxide radicals (O 2 •−) under photocatalytic for such P-CDs exhibited excellent antimicrobical effects with a high maximum reaction rate (33.3 × 10-8 M/s). Notably, P-CDs effectively inhibited the growth of both Gram-positive and Gram-negative bacteria under a 1 W white LED irradiation, especially against Gram-positive Staphylococcus aureus (S. aureus). Plate counting experiments confirmed that 75 μg/mL P-CDs could kill 98 % of E. coli when illuminated for 60 min, however, 50 μg/mL P-CDs could inhibit 100 % of S. aureus for the same illumination time. Surely, our metal-free carbon dots nanozyme provides a strong and viable alternative for the management of bacterial contamination in food security and environmental preservation, as well as a theoretical basis for P-doping to promote photocatalytic activities of carbon-dots. [ABSTRACT FROM AUTHOR]